Energy, exergy, economic and environmental comprehensive analysis and multi-objective optimization of a sustainable zero liquid discharge integrated process for fixed-bed coal gasification wastewater

Abstract

For a long time, China's regional water resource imbalance has restricted the development of coal chemical industry, and it is imperative to achieve zero liquid discharge (ZLD). Therefore, the game relationship between technical indicators, costs and emissions in ZLD process of fixed-bed coal gasification wastewater treatment process should be explored in detail. According to the accurate model, the simulation for ZLD of fixed-bed coal gasification wastewater treatment process is established, and this process is assessed from the perspective of thermodynamics, economy, and environment. The total energy consumption of ZLD process before optimization is 4.032 × 108 W. The results of exergy analysis show exergy destruction of ZLD process is 94.55%. For economic and environmental results, the total annual cost is 1.892 × 107 USD·a−1 and the total environmental impact is 4.782 × 10−8. The total energy consumption of the optimal six-step ZLD process based on multi-objective optimization is 4.028 × 108 W. The CO2 content in the treated wastewater is 0.1%. This study will have an important role in promoting the establishment of the ZLD process for coal chemistry industry.